This invention relates to the field of beverage dispensing systems. More particularly, this invention relates to the field of post mix beverage dispensing systems wherein a base fluid, such as carbonated water or plain water is to be mixed with different selected syrups to provide drinks of different flavors.
Post mix bar dispensing systems have been known in the art. These prior art systems include both electrically operated valve systems and mechanically operated valve systems. Both the electrical and mechanical systems of the prior art require separate soda valves for each syrup valve, so that the total number of valves in each system is two times the number of flavors that can be dispensed. This valving requirement of the prior art results in a larger or more bulky dispensing head, and it also increases the possibility of leakage problems.
The solenoid operated systems of the prior art are known to have both safety problems and mixing problems. The mixing problems result from the unequal opening response characteristics of the solenoid valves due to the higher viscosity of the fluid in the syrup valves. The end result of this problem is that the proper proportion of syrup and soda is not mixed, and the drink does not taste right. Prior art mechanically operated post mix dispensing systems have typically used either spool valve configurations or poppet valve configurations. Each of these valving arrangements has had a number of disadvantages or problems.
An example of a prior art spool valve system is shown in U.S. Pat. No. 3,863,810. Among the disadvantages of such spool valve systems are: they require large travel to fully open the valves; they require relatively large push forces to operate in order to overcome seal friction; they require heavy biased springs to guarantee proper return of the spool valve when the push button is released (because of friction seals); they require separate soda valves and separate in and out passages for soda for each syrup station; they require accurate machining for proper sealing; they require large residual forces to overcome the friction seal; they are difficult to machine because high accuracy is essential; and they are hard to maintain in proper operating condition. In prior art mechanical configurations using poppet valves, the arrangement has usually involved a pair of poppet valves at each syrup or flavor station (one poppet valve for syrup and one poppet valve for soda) with a bridging bar between the operating stem of the syrup valve and the operating stem of the soda valve so that soda and syrup are dispensed simultaneously. These prior art mechanical configurations have had the disadvantage that: they require two valves (one soda and one syrup) at each mixing station; they result in a bulky dispenser head because of the separate and duplicate soda valve requirements; they incorporate O-ring poppet seals which create sticking friction and require heavy return springs to guarantee proper shut-off.